1. Field of the Invention
The present invention relates to a structure for joining a ceramic plate to a metal cylindrical member.
2. Description of the Related Art
An electrostatic chuck is used as a holding member that attracts a wafer and controls the temperature of the wafer during a semiconductor manufacturing process. Known examples of such an electrostatic chuck include an electrostatic chuck in which a metal gas introduction pipe is joined to a discoid ceramic plate having a gas introduction hole so as to supply an He gas or the like from a rear side to a wafer attracting surface of the ceramic plate, thereby improving thermal conductivity (for example, PTL 1).
Meanwhile, as a method of joining a ceramic plate to a metal gas introduction pipe, a brazing method is known. In this method, brazing is performed by filling a brazing filler material in a space between a ceramic plate 110 and a gas introduction pipe 120 and applying the brazing filler material to a region from a side surface of the gas introduction pipe 120 to a rear surface of an electrostatic chuck as illustrated in FIG. 7 (for example, PTL 2). After the brazing has been performed, the brazing filler material becomes a fillet-shaped brazed part 124. In this case, stress is produced between the ceramic plate 110 and the gas introduction pipe 120 due to the difference in thermal expansion between the ceramic plate 110 and the gas introduction pipe 120. In order to reduce the stress as much as possible, the gas introduction pipe 120 is formed of a metal having a thermal expansion coefficient close to that of the ceramic plate 110.